Gender differences in age-related changes in HPA axis reactivity

Possible differences between men acid women in age-related patterns of hypo thalamic-pituitary-adrenal (HPA) axis response to challenge were examined t o test the hypothesis that women show greater age-related increase in HPA a xis reactivity to challenge. Twenty-six younger subjects, 9 men and 17 wome n, ages 22-26 and 14 older subjects, 7 men and 7 women, ages 67-88 particip ated in the study. Patterns of change in salivary "free" cortisol were meas ured in response to a standardized, 30-minute cognitive challenge, administ ered individually to each subject beginning at 1600 h, Consistent with prev ious research, there was a significant main effect for age with respect to baseline cortisol: older age was associated with higher baseline cortisol ( P = <0 .001). Results also provide support for the hypothesized age-by-gend er interaction with respect to patterns of response to challenge. There was a significant interaction with respect to maximum percentage increase over baseline (P<0.002): among younger adults, the men exhibited greater increa ses whereas among the older adults, the women exhibited greater increases. A similar, though only marginally significant pattern was seen for total ar ea under the response curve (P=0.07). Repeated measures ANOVA confirmed the gender-by-age differences in the patterns of response (P=0.01 for time*age *gender interaction). (C) 2001 Elsevier Science Ltd, All rights reserved.